# CVE-2026-28810: Predictable DNS Transaction IDs Enable Cache Poisoning in Built-in Resolver

> Attackers can poison DNS caches due to predictable transaction IDs in the Erlang/OTP built-in resolver, requiring an upgrade to secure versions.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Apr 2026
- **Updated:** 24 Jul 2026
- **Also known as:** AZL-82058, DEBIAN-CVE-2026-28810, EEF-CVE-2026-28810, GHSA-v884-5jg5-whj8, UBUNTU-CVE-2026-28810

## What is CVE-2026-28810?

CVE-2026-28810 is a medium-severity vulnerability in Erlang OTP, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Generation of Predictable Numbers or Identifiers vulnerability in Erlang/OTP kernel (inet_res, inet_db modules) allows DNS Cache Poisoning.

The built-in DNS resolver (inet_res) uses a sequential, process-global 16-bit transaction ID for UDP queries and does not implement source port randomization. Response validation relies almost entirely on this ID, making DNS cache poisoning practical for an attacker who can observe one query or predict the next ID. This conflicts with RFC 5452 recommendations for mitigating forged DNS answers.

inet_res is intended for use in trusted network environments and with trusted recursive resolvers. Earlier documentation did not clearly state this deployment assumption, which could lead users to deploy the resolver in environments where spoofed DNS responses are possible.

This vulnerability is associated with program files lib/kernel/src/inet_db.erl and lib/kernel/src/inet_res.erl.

This issue affects OTP from OTP 17.0 before OTP 28.4.2, OTP 27.3.4.10 and OTP 26.2.5.19, corresponding to kernel from 3.0 before 10.6.2, 10.2.7.4 and 9.2.4.11.

Weakness: CWE-340 (Generation of Predictable Numbers or Identifiers)

## Which versions are affected by CVE-2026-28810?

It affects 1 product.


Products: Erlang Erlang\/Otp.

## How do I fix CVE-2026-28810?

Upgrade to a fixed version.

## Is CVE-2026-28810 being exploited?

There is no known exploitation of CVE-2026-28810 in the wild and no public exploit code.

## Other vulnerabilities in Erlang OTP

- [CVE-2022-37026](https://insights.sbomify.com/CVE-2022-37026/): Auth bypass in n/a (critical 9.8)
- [CVE-2016-10253](https://insights.sbomify.com/CVE-2016-10253/): Memory corruption in n/a (critical 9.8)
- [CVE-2026-55953](https://insights.sbomify.com/CVE-2026-55953/): TLS 1.2 and DTLS client accepts unoffered anonymous cipher suite, bypassing server authentication (critical 9.1)
- [CVE-2026-49759](https://insights.sbomify.com/CVE-2026-49759/): Stack buffer overflow in SCTP error cause parsing in inet_drv allows remote VM crash (high 8.8)
- [CVE-2026-58227](https://insights.sbomify.com/CVE-2026-58227/): TLS/DTLS denial of service via unbounded recursion on cross-signed peer certificate chain (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28810 and fix it if it is affected.

What it is: CVE-2026-28810 is a medium-severity vulnerability in Erlang OTP, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-28810 in the wild and no public exploit code.

Affected product: Erlang OTP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-28810/ (Markdown: https://insights.sbomify.com/CVE-2026-28810/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28810
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28810
- OSV: https://osv.dev/vulnerability/CVE-2026-28810

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28810/
Summaries are generated and may contain mistakes; the official description above is the record.